I started doing this around 3-4 weeks ago, exactly the same, exept I'm only playing splitscreen with my GF, so no online at all. We have 5 chars (all classes exept barb and jester), all around LVL 80, no Trans armor so far. Once we beated the spider queen on InsaneHC, we started breaking on NMHC on deeper well, and got all the way up to Aquanos where the boss keeps kicking our a..es :) Doing this its been extremely fun, even more since we started NMHC.
Last night we beated NM UMF for the 1st time, after several failed attempts, on last wave, 3 minutes ~500 mobs left and we ran out our little fortress and started selling the gas trapps to have them flow faster, we finally beated it with 10 secs left and all the defenses smoking badly. None of the rewards were really good, but those 3 minutes were EPIC!
BTW our main DPS are App and Trapgirl, the weakest, :P which makes it even harder to stay alive.
Keep it up!